Heat responsive back seat arrangement for valve operator

ABSTRACT

A valve operator that is provided with a back seat which comes into use when the normally non-rising stem operator and its bearing-enclosing bonnet gland are raised, e.g. so that stem packing can be replaced, is further provided with another way to actuate the back seat, one which will come into play should the valve be subjected to heat of sufficient intensity as to call the integrity of the stem packing or other critical parts into question. The further activation mode depends on the melting of fusible material which permits the operator and its bearings to rise relative to the bonnet.

BACKGROUND OF THE INVENTION

The present invention was made as a further development of the valveshown and described in the copending U.S. Patent application of McGee,Ser. No. 800,437, filed May 25, 1977 (now U.S. Pat. No. 4,138,091) for adrive nut and torque plate assembly for the valve, the copending U.S.Patent application of McGee, et al, Ser. No. 800,438, filed May 25, 1977(now U.S. Pat. No. 4,149,558) for a selective back seat for the valve.

The foregoing, in turn, represent developments of valves described inthe following prior U.S. patents.

    ______________________________________                                        Patentee      U.S. Pat. No.                                                                              Issue Date                                         ______________________________________                                        Crain, et al  3,349,789    Oct. 31, 1967                                      McGee         3,789,875    Feb. 5, 1974                                       Boitnott      3,990,679    Nov. 9, 1976                                       ______________________________________                                    

Others have worked with fusible materials in order to provide safetydevices for valves. Examples are shown in the following prior U.S.patents:

    ______________________________________                                        Patentee      U.S. Pat. No.                                                                              Issue Date                                         ______________________________________                                        Wicke         3,771,540    Nov. 13, 1973                                      Allen         3,788,600    Jan. 29, 1974                                      Wicke         3,842,854    Oct. 22, 1974                                      Wicke         3,896,835    Jul. 29, 1975                                      ______________________________________                                    

SUMMARY OF THE INVENTION

A valve operator that is provided with a back seat which comes into usewhen the normally non-rising stem operator and its bearing-enclosingbonnet gland are raised, e.g. so that stem packing can be replaced, isfurther provided with another way to actuate the back seat, one whichwill come into play should the valve be subjected to heat of sufficientintensity as to call the integrity of the stem packing or other criticalparts into question. The further activation mode depends on the meltingof fusible material which permits the operator and its bearings to riserelative to the bonnet.

The principles of the invention will be further discussed with referenceto the drawings wherein a preferred embodiment is shown. The specificsillustrated in the drawings are intended to exemplify, rather thanlimit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings

FIG. 1 is a fragmentary vertical longitudinal sectional view of a gatevalve provided with the heat responsive back seat arrangement of theinvention. To the right of its center line the valve gate is shown in alowered, closed condition and to the left the valve gate is shown in araised, open condition.

FIG. 2 is a larger scale view of a portion of what is shown in FIG. 1 inorder to better illustrate details of the preferred heat responsive backseat arrangement.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

In the figures, there is shown a gate valve 10 having a housing 12 whichincludes a body 14. The body has a longitudinal throughbore 16 toprovide a flow passageway. At the ends of the bore 16, the body isprovided with flanges (not shown) wherewith the valve may be connectedin a conduit to provide means for controlling fluid flow through theconduit.

Intermediate the ends of the bore 16 there is provided a valve chamber20 which includes a transverse passageway which intersects with the bore16 and opens outwardly through the body at a tubular boss 22. The boss22 is provided with a flat outer end surface 24.

The housing 12 further includes a valve bonnet 26 that is mated with thesurface 24 and secured to the body, e.g. by bolts 28. A sealing ring 30is interposed between the body and bonnet to provide sealed integrityfor this juncture.

The bonnet 26 is an annular or tubular element, in the sense that it hasa coaxially disposed bore 32.

Within the chamber 20, valve seats 34 are provided at the intersectionswith the throughbore 16, and a valve gate 36 is received for slidingtransversally of the throughbore 16. The gate 36 is shown including apair of gate plates 38, and the valve is shown including an expander 40which serves to force the plates against the seats 34 when the valve isclosed, and to withdraw that force as the gate is opened.

In FIGS. 1 and 2, the gate is shown in its raised, open position at theleft, and in its lowered, closed position at the right. When the gate isopen, the openings 42 through the respective gate plates are bothaxially aligned with the valve body throughbore 16. When the gate isclosed, the blank regions of the respective gate plates are pressedagainst the respective valve seats 34.

A valve stem 44 is threadably connected to the gate and passes out ofthe housing 12 through the bore 32 of the bonnet. Outside the housing,an operator 46 is secured on the stem 44. In the instance shown, theoperator 46 is a handwheel that is designed to be manually rotated inone angular sense to raise the gate and open the valve, and to bemanually rotated in the opposite angular sense to lower the gate andclose the valve. Other operators that may be used are shown in the abovementioned prior U.S. patents of Crain et al, McGee and Boitnott.

The particular connecting means illustrated in the Figure for threadablyconnecting the gate to the valve stem are shown and described in detailin the aforementioned copending U.S. patent application of McGee, Ser.No. 800,437, filed May 25, 1977. Suffice it to say here that an upwardlyopen generally cylindrical socket 48 is formed in the gate. The socket48 includes a coaxially annular groove 50 near its upper end. Agenerally semi-cylindrical half of the socket 48 is formed in the innerside of each gate plate so the halves confront one another to constitutethe socket 48.

An internally threaded, generally tubular drive nut is shown provided at52. The drive nut 52 has a coaxially annular rib 54 formed on theexterior thereof axially intermediate the ends thereof. A coaxiallyannular flange 56 is formed on the upper end of the drive nut. The drivenut 52 is received in the socket 48 with the rib 54 projected into thegroove 50 and the flange 56 abutting the upper ends 58 of the gateplates 38. The flange 56 is radially surrounded by a torque plate 60which is pinned at 62 to each of the gate plates distally of the socket48. The radially inner surface of the plate 60 and the radially outersurface of the flange 56 are provided with splines 64. Theseinterdigitate to prevent relative rotation between the flange 56 andplate 60. Further locking means (not shown) may be provided to securethe flange 56 and plate 60 together and/or these elements may be formedintegrally and the splines 64 omitted.

Further details of the valve stem 44 and bonnet 26 will now be describedso that the structure and operation of the invention will become betterunderstood.

The bonnet 26 includes a generally radially extending base flange 66 anda tubular portion 67 extending coaxially upwardly therefrom. The bore 32passes through both portions. Where the bore 32 emerges into the valvechamber, there is a frusto-conical annular seat 68 coaxially formed atthe juncture of the bore 32 with the underside 70 of the flange 66.

A short way axially above the seat 68, the generally cylindrical bore 32undergoes a first abrupt enlargement in radius, providing a firstupwardly facing shoulder 72. Axially further up, the bore 32 undergoes asecond abrupt enlargement in radius, providing a second upwardly facingshoulder 74, within the tubular portion 67.

An axially intermediate portion of the bore 32 within the tubularportion 67 of the bonnet is internally threaded at 76. Above thethreaded portion 76, the bore 32 is provided with a radially shallow,axially broad circumferential recess 78, delimited at the top by aradially inwardly projecting annular rib 80. Above the rib 80, weatherseal 82 is provided in the bore 32.

The valve stem 44 has an externally threaded lower portion 84 that isreceived within the gate socket and threadably connected with the gateas described above. Just axially above where the stem 44 emerges throughthe drive nut 52, there is a circumferentially extending boss 86 formedcoaxially thereon. The axially upper end surface or shoulder 88 of theboss is frusto-conically tapered, complementarily with the seat 68.

In normal use, as shown in FIGS. 1 and 2, the shoulder 88 remains clearof the seat 68 and there is a significant distance located axiallybetween these two surfaces.

Above the boss 86, the stem 44 has an axially long, cylindrical,unthreaded portion 90. Axially beyond its emergence from the bore 32 ofthe bonnet, the stem undergoes a gradual reduction in radius to providea tapered band 92. Above the band 92, the stem 44 has an externallythreaded shank 94 leading to its upper end. The band 92 mounts thecomplementarily tapered hub 96 of a handwheel 98. A washer 100 and nut102 are mounted on the shank 94 to removably secure the handwheel on thestem 44.

Within the tubular portion of the bonnet, the cylindrical portion 90 ofthe stem is coaxially provided with a radially shallow, axially broadrecess 104, having opposed, facing shoulders 106, 108.

A packing assembly 110 comprising a stack of chevron packing elements isreceived in the annulus about the stem that is bottomed on the firstshoulder 72. As shown, the assembly 110 is of the type that is energizedby an injection of plastic material through an injection port 112 afterinstallation.

An annular packing gland 114 is received in the annulus about the stemthat is bottomed on the second shoulder 74 and projects therebelow,backing the packing assembly 110.

A bonnet gland 116 also is provided, generally in the form of anexteriorly threaded tubular element having an external, axiallyintermediate band of threading 118 and a throughbore 120 which undergoesan abrupt decrease in radius intermediate the axial extent thereof, toprovide a downwardly facing shoulder 122. The larger radius portionleading to the shoulder 122 constitutes a cup for receipt of the bearingassembly 124 for the valve stem. As shown, there is provided a bearingbushing 126, a washer-like annular disk of fusible material 127, aroller bearing 128, a stem split ring 130, a roller bearing 138, and aspring washer 139.

After the packing assembly and packing gland are installed, the bearingassembly and bonnet gland are installed and the bonnet gland is threadedinto place until the packing gland 114 is properly compressed.

Below the band of threading 118, the bonnet gland is coaxially providedwith a shallow circumferential recess 140. A set screw 142 is installedthrough a threaded opening 143 in the tubular portion of the bonnet 26until it projects into the recess 140. When so installed, the set screw142 prevents the bonnet gland from being rotationally backed out. (Inpractice several set screws 142 are provided angularly of the bonnet26.)

Above the band of threading 118, the bonnet gland is externallycoaxially provided with a shallow recess 144, at least including alower, generally upwardly facing shoulder 146.

A bonnet gland retainer wire 148 is snapped into the pocket formed bythe confronting recesses 144 and 78. The pocket 144, 78 is axiallylonger than the gage of the wire 148.

In day-to-day operations under normal conditions, when the valve isopened, the drive bushing 52 shoulders against the underside of theenlargement 88. Thus, the back seat does not function in normalday-to-day use of the valve.

However, in use, with the valve open and subjected to pressure of fluidbeing confined or transported in the piping system in which the valve isinstalled, a leak may occur in the packing assembly. Under suchcircumstances it may be necessary to change the packing assembly whilethe valve remains installed in the line and open.

The construction just described makes such a repair feasible, by makingthe following procedure possible.

The set screws 142 are backed out until they are withdrawn from therecess 140. Then the bonnet gland 116 is backed out a few turns, limitedby pinching of the retainer wire 148 between the upper end wall of therecess 78 and the lower end wall 146 of the recess 144.

The normally non-rising stem 44 may then be raised and tensioned to forma metal to metal seal between the shoulder 88 and the seat 68. While apositive seal remains established, the retainer wire 148 is snapped out,the gland 116 is backed out, the bearing assembly 124 is removed, thepacking gland 114 is removed, the packing assembly 110 is removed andreplaced, the packing gland 114 is reinstalled, the bearing assembly 124is reinstalled, the gland 116 is threaded mostly in and the packing 110is energized at 112. The packing is tested for leakage by reinstallingthe retainer wire 148, tightening the gland 116 and turning the stem 44which disengages the metal seal that was maintained at 88, 68.

The heat-responsive material of the annular disk 127 is a fusible,preferably metallic material, e.g. of a composition such as is disclosedin the above-mentioned patents of Allen and Wicke, and it is shownaxially interposed between the upper stem bearing and the bonnet gland.Should a fire or the like occur, such as would likely destroy the stempacking 110, the annular disk 127 will melt and its molten residue willflow out the ports P provided in communication with the site of the disk127 through the bonnet gland. Then the remainder of the valve stembearing assembly and the valve stem will rise, until the back seat isestablished at 88/68, preventing leakage. Later, the valve may berepaired, if damage is not too great, by the replacement of the packingand of the fusible annular disk 127.

It should now be apparent that the heat responsive back seat arrangementfor valve operator as described hereinabove, possesses each of theattributes set forth in the specification under the heading "Summary ofthe Invention" hereinbefore. Because it can be modified to some extentwithout departing from the principles thereof as they have been outlinedand explained in this specification, the present invention should beunderstood as encompassing all such modifications as are within thespirit and scope of the following claims.

What is claimed is:
 1. In a non-rising stem valve in which a valve bodyis mounted in a valve chamber that intersects a flow passage within avalve housing, and in which a valve stem projects out through atransverse passageway in the housing from an operative relation with thevalve body, and in which there are:means defining an annular seat onsaid valve housing within said valve chamber peripherally of where saidtransverse passageway intersects said valve chamber; means defining anannular shoulder on said valve stem spaced axially below said annularseat; a first abrupt radial enlargement in said transverse passageway,providing a first upwardly facing shoulder therein spaced axially abovesaid annular seat; a second, abrupt radial enlargement in saidtransverse passageway, providing a second upwardly facing shouldertherein spaced axially above said first upwardly facing shoulder; anannulus of packing surrounding said stem in said transverse passageway,said annulus of packing being bottomed on said first upwardly facingshoulder; an annular packing gland surrounding said stem in saidtransverse passageway, said annular packing gland being bottomed on saidsecond upwardly facing shoulder and having a tubular portion extendingdownwardly into engagement with said annulus of packing; an annularbonnet gland surrounding said stem; means providing a band of externalthreading on the bonnet gland and a band of internal threading on thehousing, within said transverse passageway, above said second upwardlyfacing shoulder, said bands being threadably engaged to compress saidpacking gland axially against said annulus of packing, bearing meansaxially positioning said stem in said valve chamber, said bearing meansbeing secured between said stem and said bonnet gland; whereby theannulus of packing may be replaced even while the valve remains open andin service, by threadably backing out the bonnet gland, axially raisingthe stem until said annular shoulder on the stem abuts and seals againstsaid annular seat on the valve housing, removing the bonnet gland,packing gland and annulus of packing from the transverse passageway,installing a sound replacement for said annulus of packing, reinstallingthe packing gland and bonnet gland, and threadably tightening the bonnetgland and again lowering the valve stem to disengage said annularshoulder on the stem from the annular seat on the valve housing, theimprovement wherein: said bearing means includes, axially interposedbetween said bearing means and said annular bonnet gland, an annulus ofheat-fusible material which is subject to melting and running awayshould the valve be subjected to a sufficiently hot event, such as afire which would leave the integrity of the annulus of packing inquestion, so that, upon melting and running away of the annulus ofheat-fusible material, the bearing means is effectively axiallyshortened by an amount sufficient to permit the valve stem to rise untilsaid annular shoulder on the stem abuts and seals against said annularseat on the valve housing; removable securement means between thehousing and the bonnet gland for preventing the bonnet gland from beingunintentionally backed out while the bonnet gland is in placecompressing said packing gland against said packing assembly, saidremovable securement means comprising bonnet gland retainer wire meanscoaxially, removably received in means defining a coaxially annularpocket between the housing, within said transverse passageway, and saidbonnet gland, the pocket being axially broader than the gage of saidretainer wire means by an amount sufficient to permit the bonnet glandto be backed out enough to permit said annular shoulder on the valvestem to engage with said annular seat on the valve housing, butinsufficient to permit further backing out of the bonnet gland unlesssaid retainer wire means is removed; means defining at least onelaterally offset passageway in said bonnet gland, each said at least onepassageway having an inner end in communication with said annulus ofheat-fusible material and an outer end opening externally of the valve,so that at least some of said annulus of heat-fusible material, uponmelting, may run away from said bearing means through said at least oneopening.
 2. The apparatus of claim 1, wherein:said annular shoulder onsaid valve stem and said annular seat on said valve housing arecomplementarily frustoconical in shape.